Coated articles are known in the art for use in window applications such as insulating glass (IG) window units, vehicle windows, and/or the like. Example non-limiting low-emissivity (low-E) coatings are illustrated and/or described in U.S. Pat. Nos. 6,723,211; 6,576,349; 6,447,891; 6,461,731; 3,682,528; 5,514,476; 5,425,861; and 2003/0150711, the disclosures of which are all hereby incorporated herein by reference.
In certain situations, designers of coated articles with low-E coatings often strive for a combination of high visible transmission, substantially neutral color, low emissivity (or emittance), low sheet resistance (Rs), and good durability. High visible transmission for example may permit coated articles to be more desirable in applications such as vehicle windshields or the like, whereas low-emissivity (low-E) and low sheet resistance (Rs) characteristics permit such coated articles to block significant amounts of IR radiation so as to reduce for example undesirable heating of vehicle or building interiors. It is often difficult to obtain high visible transmission and adequate solar control properties such as good IR blockage, combined with good durability (chemical and/or mechanical durability) because materials used to improve durability often cause undesirable drops in visible transmission and/or undesirable color shifts of the product upon heat treatment.
Low-E coatings typically include one or more IR reflecting layers. An IR reflecting layer is typically metallic or mostly metallic, and is often of a material such as silver (Ag), gold (Au), or the like. The silver or gold may be doped with other materials in certain instances. The purpose of the IR reflecting layer(s) is to block significant amounts of IR radiation, thereby preventing the same from undesirably heating up vehicle and/or building interiors which the coated article is protecting.
Generally speaking, the lower the electrical resistance (sheet resistance Rs and/or bulk resistance) of an IR reflecting layer, the better the IR reflecting characteristics thereof. However, it has heretofore been difficult to reduce resistance properties (and thus improve IR reflecting characteristics) of an IR reflecting layer without adversely affecting optical characteristics of a coated article (e.g., visible transmission, color, etc.) and/or durability of a coated article. For instances, significant changes in the thickness of an IR reflecting layer alone may affect resistance, but at the same time will adversely affect durability and/or optical characteristics of the coating.
In view of the above, it will be apparent to those skilled in the art that there exists a need in the art for a technique for reducing resistance characteristics of an IR reflecting layer(s) thereby improving IR reflecting characteristics thereof and thus solar control properties of a coated article, without significantly adversely affecting durability and/or optical characteristics of the coated article. There also exists a need in the art for a method of making such a coated article.